Good evening,

I am 16 and I am planning to do my coming out in my school in France during the last days of my year in order to begin my last year as a girl (I am currently in Première, so junior year in USA).
My parents knew about me since December 2014 and I have already told my two best friends this year. My friends are really supportive as well for my parents, and i started to take androcur in May. I will be allowed to take hormones in May or June maybe next year and I was thinking of doing a kind of speech in front of my class to come out of the closet.
All of my classmates are very nice and I already know that I will keep the same class next year.
Many people in my school started to ask questions about me ( not directly but in my back) about my appearance because I am quite feminine and due to my small frame and height, it enhanced it therefore I am afraid for the next few mounths because I will not know what to say when I will be confronted about it.

Anyway, I just wanted to have some advices of how should I present my speech, do I just say directly : Hey, you probably notice that I am not like the other boys. Well, I am transgender.
And then I explain further?

Thank you!
PS : I apologize for the eventual misspellings.

As you have already come out to a number of people, think about the approach you used with them. The best way to do public speaking if you are new to it is pick out somebody in the audience and speak to that person just as if that were the only person in the room. A little bit of history before hand will help the people what you are about to say is important to you and this is not something new but instead something you have thought about for a long time. You want to give them that little part of you that you want to share just as you did with the friends you already told.

When I came out at work, I gave a 30 second speech to my administrators:

There are some people whose brain tells them to act and present as the gender opposite their physical sex. We don't know what causes it, but the current theory is that it happens before birth. It doesn't go away on its own and no one has ever found a way to make someone no longer transgender. However transitioning to live as the opposite gender is a recognized treatment that can be very effective.

Well I think you are very very brave to put it in a speech, because I seriously couldn't have done that coming out. I would get it out first, and then explain afterwards, because that follows the brain process the closest. (e.g. people will hear it and then be like ?)
You are SO brave!